Support more Cross-Origin headers

[woodruffw]

There are at least two more security relevant headers that we should test for and produce judgements on:

• Cross-Origin-Opener-Policy
• Cross-Origin-Embedder-Policy

More resources:

• https://hacks.mozilla.org/2020/07/safely-reviving-shared-memory/
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Opener-Policy
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Embedder-Policy

[GatewayBit]

Hello, @woodruffw
I would be interested in picking up this task.

[woodruffw]

@GatewayBit sure!